Cranberry Juice and Health

If new research data supports earlier findings, for some people the key to preventing
a urinary tract infection may be as simple as a visit to the grocery store.

Millions of people suffer yearly from these painful infections, says Cibele Barbosa-Cesnik,
a research investigator in the Department of Epidemiology. In fact, only respiratory
infections are more prevalent. And women are especially vulnerable. According to a
study by SPH Professor Betsy Foxman, 11 percent of women over the age of 18 suffer from UTIs, and many of these infections
are recurrent.

What’s more, says Barbosa-Cesnik, in the past 15 years UTIs have become increasingly
resistant to common antibiotics, so researchers are looking for new ways to prevent
infections. Barbosa-Cesnik is focusing on one potential solution: cranberry juice.

Most UTIs, she explains, stem from one type of bacteria, Escherichia coli (E. coli),
which typically inhabits the colon but often adheres to the bladder, causing infections
to develop. A number of in vitro studies suggest that proanthocyanidins, or PAC, a
component of ordinary cranberry juice, inhibits the adherence of E. coli bacteria
to the bladder. “If it can’t adhere,” says Barbosa-Cesnik, “it’s washed out.”

In a four-year study funded by the National Center for Complementary and Alternative
Medicine, a division of the National Institutes of Health, Barbosa-Cesnik is studying
the ability of cranberry juice to inhibit UTIs in college-aged women, a population
that is particularly prone to UTIs, in part because the infections can be sexually
transmitted. Foxman is a co-investigator on the study.

For a period of six months, the 400 participants in Barbosa-Cesnik’s randomized study
will drink either eight ounces of cranberry juice or a placebo juice twice daily.
Researchers will monitor relevant symptoms in the participants and ultimately analyze
the data they collect. Barbosa-Cesnik is seeking to determine whether cranberry juice
reduces UTI recurrence within six months, whether it helps UTI patients heal faster,
and whether it selects for a less-virulent bacteria. Morton Brown, professor of biostatistics,
directs the study’s Data Coordinating Center.

If cranberry juice turns out to be an effective means of preventing UTIs and of halting
recurrent infections, she says, at-risk patients could begin drinking more juice as
a preventive measure, and doctors could begin prescribing the juice as part of a daily
diet regimen.

The study is one of several throughout the nation that are looking at the effect of
cranberry juice in populations susceptible to UTIs, including pregnant women. “There’s
a lot of interest in this,” Barbosa-Cesnik says.

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Studies suggest that a component of ordinary cranberry juice inhibits the adherence
of E. coli bacteria to the bladder.